Introduction

Emergency is one of the most important parts of a hospital. The operational and effective function of the Emergencies can have a great effect on the quality and quantity of the operation of other departments and satisfaction of the people who receive healthcare services [1]. Because of its importance and sensitivity Emergency in each hospital must be structurally and organizationally set in order to give the healthcare processes carefully and with a high quality and have a suitable function in presenting services to patients [2]. Emergency is a department that patients often get their first experience of the hospital there [3, 4]. During last years, because of the population increase, increase in intentional and unintentional harms and drugs abuse Emergency departments in hospitals have lots of costumers, but number of these parts has not increased that much [5-7]. Emergency departments face with a serious problem of not presenting suitable healthcare services, because of the demographic changes of the population and the appearance of the illnesses such as increase in age average and hope for life, outbreak of ailments such as cancers and heart diseases, and at the same time since people have got more knowledge in relation to the growth and keep of health, they want to receive high qualified and high quantity of health cares in Emergency departments [8-10].
In order to solve the problem of patients’ high numbers in Emergency departments and after that problems of high qualified healthcare services most of the managers of the healthcare systems and deciders think that implementing quality improvement models for reaching to this goal is inevitable. Lean management is one of the methods that have been very popular in the last two decades [11-13]. Lean management is a term used in industry to improve the production capacity and omit wastes in the process and has been well known especially after being implemented by Toyota. By developing the success of this method of management, other organizations such as hospitals used its principles to make their work process reliable and stable and get achievements in work capacity increase, costs decrease, costumers’, staff’s satisfaction and reinforcing leadership [14-16]. Although the healthcare part got involved in Lean management later, but recently many healthcare organizations implement this method and have been able to make impressive improvement in offering qualified services to patients and reduce costs, damages and wastes, and these results got possible just by cultural preparation and gradual improvement [17-18]. Lean management includes five main principles, its guidance and instruction and it leads the company and the organization which present a service or product toward a stable and seeking system. The main principle in Lean is to delete the production wastes. In Lean management costumer has a very important place and it believes that for improving the system and considering the costumer and improving the value we have to forget our competitors and concentrate just on ourselves. We should recognize the wastes and delete it and then with a perfectionisms approach stay in the improvement cycle [19, 20].
In recent years many researches have been done and designed in hospitals, especially the Emergency departments by using the lean management and the results show the impressive effect of this management method in improving the services quality to patients [21-27]. Since this management method is newly implemented in hospitals and the Emergency units are very important, in choosing and applying this method we should have precise and enough information about the previous researches’ properties and results. We should also analyze the important factors in success or probable failure of this method. Hence the present study is planned to review the properties and the results of the previous studies with Lean management approach in Emergency units and the effective elements in implementing that.

Materials and Methods

Search Strategy
This study is a systematic review done in 2016 and has used the systematic review of studying from the book named “Systematic reviews to support evidence based Medicine” [28]. We collected the necessary information in the first step by searching these key words “Lean principles”, “Lean Six Sigma”, “Lean Process”, “Lean thinking”, “Lean Methodology”, “Toyota Production System lean processing”, “lean techniques”, “emergency department”, “emergency medicine”, “emergency room” and “emergency care " in PubMed, web of Knowledge, Google Scholar, Scopus database and in the second step by using “Lean management” and “Emergency” in SID, Medlib, IranDoc, Google Scholar, MagIran, IranMedex. Time period for searching these articles was 2000 to 2016. After searching these data bases, in order to identify and cover most of the published articles we searched some of the authentic magazines (Am J Med Qual, BMC Health Serv Res, Int J Health Care Qual Assur, J Healthc Qual, Jt Comm J Qual Patient Saf, Qual Manag Health Care, and World Hosp Health Serv). After deleting the essays having weak connection with the study and choosing the main essays, the references of the chosen essays were searched again to make sure that we have chosen the right ones.

Inclusion and Exclusion Criteria
The eligibility criteria for include or exclude of articles are summaries in Table1.

 Table 1. Inclusion and excluded criteria.

Data Extraction 
Quality of the report in selected essays was evaluated after getting extracted from the databases by using the mentioned key words. The check list of (STROBE) Strengthening the Reporting of Observational and studies in Epidemiology was helpful here. For extracting the data first, we prepared two data-extracting forms in Excel. First form was for the descriptive studies section including: writer, country, publishing year, words applied, duration of the Lean management implementation, type of study, members of the Lean management team, assessable indicators and the total conclusion of the research. First data of the 5 essays were extracted experimentally for the form and the inefficiencies and problems of the present form were solved. The second form was allocated for the information about the barriers/challenges, facilitators/ success factors and effective factors. The information extracted in this form was: writer, country, publishing year, barriers/challenges, facilitators/ success factors and effective factors.
Data Analysis
The information we got from the forms first was organized in information-extracting forms and was analyzed manually. The diagrams were drawn in Excel:2010.

Results

Eventually from the 696 essays, 26 essays that had a link with the purpose of the study were selected (Figure 1).

Fig 1. Searches and inclusion process.

Descriptive results of the Lean management implementation in Emergency departments are shown in Table 2. 

As we can see in Table 2 most of the studies in this department are done in the U.S.A: 12 of 23 studies, Canada with 3 studies, England 2 studies, China 1 study, and Australia 1 study. Spain 1 study, Sweden 1 study, Netherland 1 study and Lebanon 1 study. Most of these studies are done after 2010.
Different terms were used for Lean management in different studies. These terms are shown in Figure 2 according to the numbers of repetition. As you can see, Lean techniques and lean principles are five more times repeated and stand in the first place.
Among 23 studies evaluated in this part of our study, we could extract the duration of implementing the Lean management in 16 studies. According to the findings the longest time of implementing Lean management was for the study of Richardson et al., [29] hat was 40 months. And the shortest time was 1 month in Mazzocato et al., [30]. Totally in all 16 studies Lean management was run for 198 months (12.3 months’ average for each study). The average time for implementing the Lean management was 10 months.
18 studies from 23 studies were done evaluating the last and next assessments. 3 studies analyzed the results after implementing the Lean management cross-sectionally. In one study time series studies were applied. Only in one of the studies controlled studies were used. The most important members of implementing lean management included: the hospital management team or the Emergency department head, physicians, nurses, staffs and external counselors. In the assessment, totally we mentioned 51 indicators shown in Figure 3 according to the repeating times. As it is seen length of stay and timing have the most frequency among the studies.
Nearly all the evaluated indicators in the studies have made a noticeable improvement after implementing the Lean management. In all of the studies length of stay both in discharged patients and hospitalized patients have been reduced. Time duration of doing the first treatments in the first possible time had a considerable reduction. Also the waiting time in emergency department was lower. Patients’ satisfaction had a rise too. Ed without being seen by a doctor (LWBS) in the Emergency department had an appreciable reduction. In two studies focusing on the expenses it was shown that they had costs’ decrease.
7 studies pointed to the barriers/challenges, facilitators/ and successes and failure factors in Lean management implementation (Table 3). Among them we see 2 essays in U.S.A, 1 in Ghana, 1 in England, 1 in Sweden, 1 in New Zealand and 1 in Lebanon. 4 studies worked on the barriers, 4 studies on facilitators and 2 studies pointed to the effective factors. In Lean management 14 barriers, 14 facilitators and 10 effective factors were identified.   By content analysis the barriers/challenges, facilitators/success and effective factors in Lean management were classified in the framework of Figure 4.

Table 2. Descriptive results in implementing lean in hospitals’ emergency units.

Fig. 2. Different terms which were used in lean management.

Fig. 3. Evaluated indicators in studying the lean management in hospitals’ emergency units.

Table 3. Barriers/ challenges, facilitators/ success factors and effective factors in implementing lean management in emergency units.

 Fig. 4. Barriers/ challenges, facilitators/ success factors and effective factors in implementing lean management in emergency units.

Discussion

In applying the methods of quality improvement such as lean management, the Emergency department, because of providing extended services for patients as well as its special place in quality of hospital service and customer satisfaction has great importance. In most cases the Emergency department is the first experience of patients. And since the patients need special and immediate caring and treatment, understanding the patients’ problem in this department is highly necessary for gaining their satisfaction. In recent decades, several factors such as population growth, increasing intentional and unintentional harms and drug abuse have increased the number of emergency unit’s clients. But the number of emergency units has not increased that much in the period [53, 54].
In the study among 696 recognized essays, finally 26 essays were selected (23 of them were related to descriptive section and 7 of them were related to section of factors [some of these essays were in both categories]). Most of the studies were accomplished after 2010 in Canada and United State. Among the 23 descriptive studies, 18 of them were accomplished before and after lean implementation. And 3 of them surveyed the result only after the implementation. Two terms of “lean techniques” and “lean principals”, with five repetitions had the highest frequency. The most important members of implementing team of lean management were hospital management team or the Emergency department head, physicians, nurses, staffs and external counselors. Generally, 51 indicators were studied which among them the length of stay and the timing had the most frequency. After lean management implementation, almost all studied indicators have significantly improved. 7 essays pointed to barriers/challenges, facilitator/success factors and effective factors in implementing lean in Emergency department; and 14 barriers, 14 facilitators and 10 effective factors were recognized in implementing lean management.           
Studies’ results show that like most of the improving quality models, lean management approach has been more considered in the developed countries. This is more explicit in the models like lean management which has their root in industry; because there are many developed industry in such countries. Hence, the developing countries which demand to use these models must use these models cautiously and vocalize them according to their economic and cultural conditions and especially according to their health systems.
Two terms of “lean techniques” and “lean principals”, with five repetitions had the highest frequency. Regarding the importance of common language in methods of improving quality [55], to gain a common language in lean management can have an effective role in its well implementing.
Among the 23 descriptive studies, 18 of them were accomplished before and after lean implementation. Only in 1 study, the control group was used. Because of the equality of conditions in after and before assessments, the corruption chance of interventions results is really high, so the use of a control group in interventional studies is proposed in order to minimize the effect of confounders as well as increasing the ability of comprising and analyzing the result [56, 57]. Therefore, we propose that future studies use a control group.
Among the different indicators surveyed in these studies, the length of stay and the timing had the highest frequency. In precise focusing on types and frequencies of the used indicators it has been considered that the lean management in these studies focuses more on indicators relating to the time (time of the first offering service, waiting time, hospitalization time, circulation time). The main reason of this can be extension, importance and easy improvement of time indicators [58- 60]. Considering the shortage of recourses and time as well as the complication of measuring and improving the other indicators, the time indicators can be good samples for intervention and improvement. However beside this, we shouldn’t ignore the importance and place of the other indicators such as financial ones and indicators related to the patient satisfaction and efficiency.
The most important members of implementing team of lean management were hospital management team or the head of Emergency department, physicians, nurses, staffs and external counselors. One of the most important persons in implementing lean management is the external consultant who is expert in this field. Since the lean management is a model rooted in industry and has its special complications, and staffs in health systems especially Emergency department are not familiar with dimension and complications of the model; so it seems that it is necessary to use the consultants and experts of the model in lean management group [61]. The other important member of the group is organization’s senior manager with his/her responsibility. Lean management makes a great change in offering services and management style in each department; and it is obvious that any change requires the organization senior manager responsibility. Otherwise, not only there will be many organizational and structural problems in implementing the project, but also others will lose their motivation for implementing lean [62,63].
One of the personal barriers for implementing lean management addressed in the studies was the resistance against the change which in studying other department often had been addressed [64-67]. Since the implementation of lean management is an invisible change, the staff resistance is apparently inevitable. But it is required to decrease the staff resistance with different ways such as considering their feeling, talking with them, trusting them and giving them the freedom [68-70]. For there is no doubt that lean management like other intervention in hospitals and health systems, will be unsuccessful by resistance of staffs and without their cooperation.
Another barrier is that the origin of the lean management is in industry and it doesn’t have enough compatibility with health system. One of the most important results of the barrier is the shortage of knowledge about the model in health system. Poksinska who studied the lean management position in health system pointed that this shortage of knowledge of lean management in health system could be due to the origin of the model [64]. It is pointed out that it is better for lean management team to include external consultant and experts of lean management. So it seems that using these experts and consultants as trainers of the model beside implementing the
Lean management can be a good solution for the barrier. But the problem of using these experts is that they are not familiar with health system and they use technical and industrial language [71]. So it is better to work with a team in training. Namely such a group should be included both the experts of health systems and the experts of lean management. Furthermore, as it is stated in the section of the effective factors, the adaptation of the model with native condition can make the performance of the model better.
Another limitation of the study was the language, because researchers could search for only English and Persian studies. Furthermore because of the great inconsistency in implementing the studies and their results, it was impossible to apply the Meta analyses. 

Conclusion

Countries with high income had numerous experiences in implementing lean management; so transferring such experiences to low-income countries will have a great role in successfully implementing lean management in these countries. This study suggests further studies in lean management in emergency departments by using control groups. In order to successfully extend lean management in health system especially in Emergency departments, it is necessary to reach to a common language between researchers, health services providers, health systems managers and programmers. According to the results of the studies some factors which have a great role in lean management are: responsibility of the senior management and his/her supports, increasing the knowledge of health services providers about the properties and the dimensions of lean management, decreasing staff’s resistance and using the consultants and experts in the field.

Acknowledgments

This study was part of a PhD thesis supported by Iran University of Medical Sciences, International Campus (Grant No: IUMS/SHMIS-I. 9223652208/2016).

Funding: This study was funded by Iran University of Medical Sciences.

Conflicts of interest: The authors declare that they have no competing interests.